U.S. Pat. No. 4,001,742 entitled "Circuit Breaker Having Improved Operating Mechanism" describes a circuit breaker capable of interrupting several thousand amperes of circuit current at several hundred volts potential. As described therein, the operating mechanism is in the form of a pair of powerful operating springs that are restrained from separating the circuit breaker contacts by means of a latching system. Once the operating mechanism has responded to separate the contacts, the operating springs must be recharged to supply sufficient motive force to the movable contact arms that carry the contacts.
U.S. Patent Application entitled "Operating mechanism for high ampere-rated circuit breaker" application Ser. No. 08/202,140 filed Feb. 25, 1994, describes an operating mechanism capable of immediately resetting the circuit breaker operating mechanism to reclose the contacts without having to recharge the circuit breaker operating springs immediately after opening the circuit breaker contacts.
U.S. Patent Application entitled "Rating module unit for high ampere-rated circuit breaker" application Ser. No. 08/203,062 filed Feb. 28, 1994, describes a circuit breaker closing spring modular unit whereby the circuit breaker operating springs are contained within a separate unit from the operating mechanism and can be installed within the circuit breaker enclosure without disturbing the operating mechanism assembly,
U.S. Patent Application entitled "Handle operator assembly for high ampere-rated circuit breaker" (41PR-7130) describes a handle operator unit capable of generating large spring charging forces by means of an externally-accessible manually operated handle. A ratchet and pawl assembly allows the manually-applied charging forces to be applied to the operating springs. Once the circuit breaker operating mechanism closing springs are fully-charged, some means must be employed to release the pawl to allow the closing springs to become fully operational.
The charging of the powerful operating springs controlling the circuit breaker contacts is made manually by means of a ratchet and pawl assembly. A two stage latching arrangement controls the retention and release of the pawl to retain and discharge the operating springs as described in U.S. Patent Application entitled "Latching arrangement for high ampere-rated circuit breaker operating springs" application Ser. No. 08/218,287 filed Mar. 28, 1994.
Since separate pairs of operating springs are used to close and to open the circuit breaker contacts, it is important to prevent any attempt to close and open the circuit breaker contacts simultaneously.
Prior attempts to discourage depressing the closing and opening buttons that were externally accessible included remotely positioning the buttons from each other on the circuit breaker cover. However, with the streamlined operating mechanism described within the aforementioned U.S. Patent Applications, the operating mechanism components interact with the accessories that are mounted within the circuit breaker cover next to the electronic trip unit. To efficiently couple the operating mechanism components with the accessories and with the electronic trip unit, it is preferable to arrange the closing and opening buttons alongside each other.
One purpose of the invention is to provide an interlock arrangement between the closing and opening components that responds to the closing and opening buttons that will reliably prevent both buttons from being operated simultaneously.